Scalable quantum photonic technologies require combining a wide variety of functional components which are capable of generating, manipulating and measuring quantum states of light. Integrated photonics provides a means to do so, in a compact and resource efficient manner. Nevertheless, the operating conditions for all constituent components must be mutually compatible in order to function effectively. While nonlinear- and electro-optics are well established methods for generating and manipulating quantum states of light at room temperature, single-photon level measurements are best performed with detectors relying on photon-induced breakdown of superconductivity, which necessitates their operating in a cryostat at temperatures around 1-4K. For full integration, as well as specific components requiring both detectors and modulators in close proximity, photonic devices must be made compatible with cryogenic operating conditions.

In my group we have made progress demonstrating a broad range of cryogenic quantum photonic components, namely parametric down-conversion for sources of quantum light, nonlinear frequency conversion, electrooptic phase and polarisation modulation, electrooptic routing and integration of various types of superconducting detector, all on the lithium niobate platform. This demonstrates the feasibility of this platform for many key applications of integrated photonics in particular feed-forward.